Paperboard drinking cups and the like are conventionally formed from a blank having opposed longitudinal edges arced to define, upon a rolling of the blank, a circular cup mouth and a relatively smaller circular cup base with the cup body tapering therebetween. The arcs of the opposed longitudinal edges are formed on different radii in accord with the diameter of the cup at the mouth and base. As such, the radius of the arc of the base edge is conventionally appreciably less than the radius of the arc of the mouth edge. For example, in one form of standard 32 ounce cup, the radius for the mouth edge will be 24.9611 inches while the radius for the base edge will be 17.207 inches.
In forming the cup from the blank, the mouth edge will be outwardly rolled to define a lip. The base edge will be inwardly folded and appropriately crimped and bonded to a bottom panel, and usually to a depending peripheral flange thereon. The conventional blank incorporates more than sufficient material to accommodate the edge forming.
In actually producing the blanks, paperboard is supplied from a roll with lengths thereof cut by knife blades, for example in the form of die plates, roller dies, or the like, to simultaneously define a continuous series of blanks in adjacent longitudinal rows.
The blanks in each row are alternately inverted with the opposed longitudinal edges thereof defined by a separate pair of sinuous cut lines each alternately defining a convex mouth edge and a concave base edge of differing radii. The longitudinally aligned adjacent blanks in each line are defined by transverse edge cuts inclined to extend between the longitudinal lines at approximately the transition point between adjacent convex and concave lengths.
The blanks in adjacent rows are transversely aligned across the width of the length or sheet of paperboard with each row defined by two distinct longitudinal cut lines and with the adjacent cut lines of adjacent rows spaced from each other to accommodate the alternate arcs of different radii. As will be appreciated, this spacing, for example on the order of 1/4 inch, produces substantial scrap which is not only in itself expensive but also gives rise to problems in the retrieval and disposal of the scraps.
It will also be recognized that the space necessitated between adjacent rows requires immediately adjacent substantially duplicate cutting blades or assemblies between each adjacent pair of rows. This in turn substantially affects the cost of the equipment, the speed at which the equipment can be run, maintenance problems, and the like.
While it is known to use blanks for short wide ice cream containers with outer mouth and inner base edges formed on common or duplicate radii, such blanks, if cut from sheets as above described, would still require spacing between adjacent rows to accommodate the opposed arcs of the outer edges of adjacent blanks in adjacent rows as shall be explained subsequently.